This invention relates to an image scanner apparatus with scanning function and, more particularly, to an apparatus for scanning an image of an original, which is filed by an image data file unit, in a two-dimensional manner.
When an original image is to be scanned, a conventional image scanner apparatus of an image data file unit performs binary coding by means of a simple binary or dither binary means. A character portion on the original is scanned by simple binary coding means and a non-alphanumeric character portion, such as a photo, is scanned by dither binary coding means or the like.
However, it is not convenient to divide an original having character and photo portions into separate portions to effect scanning of the original by merely using separate binary coding means. Therefore, when character and photo portions are mixed in a single original, often, only the character or photo portion can be correctly scanned.
A scanner wherein an original is divided into character and photo portions and binary coding is performed using separate binary coding means has the following problem.
A scanner of this type changes the level of an image signal in accordance with the density of the background of image data corresponding to the original. More specifically, an image signal is divided by a level obtained by subjecting the image signal to peak hold, thereby performing gain control and simple binary coding at a predetermined slice level. When such an image signal is to be subjected to binary coding using a dither method or the like, however, since the level of the image signal changes in accordance with the density of the background, correct gradation cannot be obtained. In other words, a photo portion cannot be subjected to optimum binary coding.
In addition, since character and photo portions are scanned based on the same thickness standards, they cannot be scanned in an optimum manner.
Furthermore, in the original scanner apparatus as described above, when area designation is to be performed to divided a single original into character and photo portions, an area designation key must be provided on an operation panel. This renders the operation panel complex, and an input operation of area designation data becomes cumbersome. If area designation data is input during original scanning, processing of the apparatus becomes complex. Also, area designation data cannot be stored.